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The Last Machine or What I Learned from the “Book of Knowledge of Ingenious Mechanical Devices”

Introduction

The “Goblet which arbitrates during drinking parties” is my fiftieth machine and the last I have left in the Book of Knowledge of Ingenious Mechanical Devices. It is almost identical to this goblet, and anyone who wants to learn about it will find all the explanations there, accompanied by a discussion of alcohol in the Middle Ages.

I published my first post, “The Peacock Clock and the Beauty in Engineering”  a few years ago. My friend, Dr. Oved Kedem, retired, and I was looking for a parting gift for a man who loves science and the history of science. I came across the book, fell under his spell, and am still captivated. When I set out, I thought about publishing one of al-Jazari’s machines at a time, along with simple explanations that would clarify its mechanism and its place in the history of technology. In the meantime, I embarked on a breathtaking cultural journey in the 12th century; this post is a pocket dictionary of my journey.

Dictionary (sorted by the letters in the Hebrew alphabet)

א – Aleph – Automatons ( in Hebrew אוטומטון)  – A self-operating machine; automatons are not an invention of al-Jazari. Evidence of the first self-operating mechanical dolls comes from ancient Greece (Greek: αὐτόματον – “moving by itself”), but al-Jazari developed and greatly refined the field of automata. He was the first to use camshafts, as seen in the Musical Boat and the Castle Clock. He cleverly combined tooth wheels, siphons, and balancing weights and built a very wide range of machines; From the automaton that drinks the king’s leaving to the Monk Basin for measuring the amount of blood during bloodletting. I wrote here about the magic of al-Jazari’s mechanical dolls and their relation to the golden age of automatons in the 18th century.

ב – Bet – Falcons ( in Hebrew בזים) – For an engineering book that focuses on fine mechanics and control, I found a great wealth of animals. There is an elephant, a lion, and a monkey, several unidentified birds, six peacocks (!)  A nameless fish, an unspecified domestic beast (دابّة – dabbah), two cows, and five dragons. But the large number of appearances in the book, to my great surprise, belongs to Falcons; there are seven falcons in the book. Falconry was a major sport in the Artuqid court. We can read about the special relations between the hunters and their trained birds of prey in “The Book of Contemplation” (كتاب الاعتبار) by Usama ibn Munqidh (أسامة ابن منقذ), a poet, writer, and knight who lived at the Artuqid court a few years before al-Jazari.

Falcon casting bronze balls, The Castle Clock, Topkapi Manuscript, 1206

ג – Gimel – Water Wheel (in Hebrew גלגל מים) – This revolutionary water pump is the fifth  pump in Category V, which is dedicated to “machines for raising water from pools, and from wells which are not deep, and from running streams.” The pump’s power source is a water wheel located in the river, which rotates under the force of the flowing water. There are three major innovations in al-Jazari’s pump in comparison to previous pumps:

  • Al-Jazari uses the power of the river to operate the pump, while Ctesibius’ pump required a man to operate it. This was a great advantage for pumps for drinking water or irrigation.
  • The use of a water wheel required converting the circular motion (the water wheel) to linear motion (the movement of the pistons). Al-Jazari improved the slider-crank mechanism, which remains in use to this day without significant changes.
  • Al-Jazari used suction pipes allowing the pump to function well even in the event of a drop in the water level.

Aba Neeman, great-grandfather of my beloved M., built the first pump factory in Israel. Oddly enough, almost the only difference between al-Jazari’s pump and Abba Neeman’s pump is that the latter is powered by a diesel engine and the former by a water wheel.

ד – Dalet – Dragon – (In Hebrew (דרקון  – The boat clock looks like an early sketch for the elephant clock or a simpler version for beginners. It has a scribe indicating the passing minutes and a single dragon, as opposed to two in the elephant clock, which rotates on its axis once every half hour. Al-Jazari refers to him as a serpent, but the legs and wings make him a dragon.

 ה– He – The bloodletting (in Hebrew הקזת דם) – bloodletting was common among many ancient peoples: in Greece, Egypt, and Mesopotamia. Islamic medicine preserved and developed the medical knowledge of the classical period and the main traditions of Hippocrates, Galen, and others. Al-Jazari designed four different devices to measure the amount of blood drained. We have a lot of medical information as well as visual documentation of bloodletting. There is no vessel that “foreshadows” al-Jazari’s basins, and all the vessels after him are simply bowls, at most with ticks. My explanation is here.

וו- Vav – Wudu (In Hebrew וודוא  – (The third category of the book describes five tools for the ablution ceremony (Wudu), including a peacock which discharges water from its beak, an “automatic” basin without human involvement, and an automaton of a young slave holding a jug of water in one hand with a towel and a comb. To the best of my knowledge, there are no other examples of automatons or other “patents” for the ablution ceremony before or after al-Jazari. Al-Jazari’s multitude of tools for purification may attest to the importance of the ceremony in the Artuqid courtyard in Diyarbakir and/or al-Jazari’s passion for automata that used his favorite siphons and buoys

The peacock which discharges water from its beak. Topkapi manuscript, 1206.

ז – Zain-Time (In Hebrew זמן) – Al-Jazari was deeply engaged in timekeeping; the book’s first category describes ten water and candle clocks. Some of these—such as the Scribe water clock—measure solar hours; i.e., both daylight and nighttime were divided into exactly 12 hours each. This means that at the peak of summer in Diyarbakır, there are 14.5 “normal” hours of daylight, and a solar hour is about 12 minutes longer than the hour we are accustomed to. Others—such as The Candle Clock of the Swordsman —measure the fixed hours we know today. In the 21st century, the concept of solar hours seems very strange and unnecessarily complicated. Yet it is worth remembering that timekeeping has always relied on the movement of celestial bodies: years were counted by the sun or the moon, while the day, hour, minute, and second were all derived from the celestial clock.

ח – khet- The Perpetual Flute (In Hebrew חליל מתמיד) – The “Book of Knowledge of Ingenious Mechanical Devices” describes four perpetual flutes that operate using the movement of water to compress air, thereby replacing the human player. Al-Jazari cites three sources for his work: Apollonius the Indian carpenter, a drawing from an unknown source, and a treatise by the renowned inventor Hibat Allah al-Asturlabi. The use of three distinct sources for the perpetual flute suggests to me that Al-Jazari possessed quite an impressive library. Was there a library in the palace? One with shelves dedicated to engineering and technology? Who else besides him read those books? It is a pity we have no answers. More information on medieval libraries and books can be found here.

ט – Tet- Peacocks (In Hebrew טווסים) –There are quite a few peacocks in the “Book of Knowledge of Ingenious Mechanical Devices”: The Peacock Clock, The Peacock which Discharges Water from its Beak, and the Basin of the Peacock. The peacock appears in Greek mythology, holds a central place in the Yazidi religion, and is also held in special regard in Islam. I particularly liked the following sermon by Imam Ali:

“The peacock struts proudly and haughtily, raising its tail and spreading its wings, laughing as others marvel at the beauty of its plumage and the splendor of its jeweled adornments. Yet, when it gazes at its legs, it cries out loudly for help—filled with genuine sorrow—for its legs are as slender as those of a crossbred rooster from India and Persia.”

This bears a striking resemblance to the Yiddish proverb:

“Az di fave kukt oyf ire federn – kvelt zi, ober az zi kukt oyf ire dare fis – veynt zi “

Which means: “When the peacock looks at its feathers – it rejoices, but when it looks at its thin feet – it weeps” [In Yiddish, the peacock is always referred to in the feminine; Eastern European Jews did not excel at zoology.]

י – Yud- Wine (In Hebrew יין) – I am no expert on Islam, yet the boisterous drinking parties in Diyarbakır and the casual attitude toward alcohol consumption took me by surprise. The Goblet which arbitrates during drinking parties stands as clear evidence that the Artuqid court in Diyarbakır lived quite comfortably with this contradiction. While the book contains abundant references to Islam and its customs, it simultaneously depicts banquets filled with games and merriment—conducted without a hint of apology or concealment. The Artuqid rulers lived among a diverse local population—including Armenians, Syrians, and Greeks—many of whom were Eastern Christians. In Christianity, wine is not merely permitted; it is a liturgical element. It is possible that this shared existence fostered a more lenient attitude toward wine consumption. Then again, I might simply be projecting the strictness of the modern-day prohibition onto a different era.

 

כ – Kaf- Scribe (In Hebrew כתבן) – The Scribe (ورّاق) or a book copier appears in three of Al-Jazari’s clocks—the Scribe Water Clock, the Scribe Candle Clock, and the Elephant Clock. The scribe was a significant figure in medieval Muslim society. This stemmed primarily from the Quran’s importance and, consequently, from the central role of books in general. Since Islam was conveyed to humanity in Arabic, both the language and the Arabic script are considered sacred. In the Muslim worldview, the act of writing parallels the work of the Jewish ritual scribe (*sofer stam*). For medieval Muslims, calligraphy represented the highest form of art—the art of the spiritual realm—bridging the gap between language and religion.

The Scribe’s Water Clock—likely a dispersed manuscript from Cairo,1354.

ל – Lamed– Schooling (In Hebrew לימודים) – Regarding his education—we have no information about Al-Jazari other than what appears in the text itself; he says nothing about his childhood and very little about his education:

” have studied the books of the earlier [scholars] and the works of the later [craftsmen] -masters of ingenious devices with movements like pneumatic [movements], and water machines for the constant and solar hours, and the transfer by bodies of bodies from their natural positions. I have contemplated in isolation and in company the implications of proofs. I considered the treatment of this craft for a period of time and I progressed, by practicing it, from the stage of book learning to that of witnessing”

Al-Jazari likely received a basic education between the ages of six and ten, as was customary in the Muslim world. The foundation of this schooling was the Quran. After these four mandatory years, most students either worked alongside their parents in agriculture or apprenticed with master craftsmen. Unfortunately, Al-Jazari writes nothing about this chapter of his life. It is a pity; I would be very interested to know about his experiences as an apprentice.

מ – Mem– Water Pumps (In Hebrew משאבות) – The fifth section features five water pumps. This section focuses on the engineering core—improving process efficiency—whereas most of the other chapters deal with surprising automata and rotating peacocks. For most of Al-Jazari’s machines, the question of efficiency seems out of place, perhaps belonging to an entirely different discipline. A process is considered efficient if the amount of work performed increases while resource consumption (raw materials, time, labor, fuel, etc.) decreases; yet Al-Jazari is an engineer at heart, and when it comes to water pumping, he proposed impressive efficiency improvements.

נ – Nun– Paper (In Hebrew נייר) – Paper was invented in ancient China. Legend has it that two Chinese captives, taken by the Abbasid Empire following its victory at the Battle of Talas in 751 CE, secured their freedom by revealing the secret of papermaking. Regardless of the story’s veracity, a dramatic paper revolution swept through the Muslim world during the ninth and tenth centuries. The Chinese art of papermaking was refined and mechanized: flax replaced mulberry bark, the soaking process was improved, and the mallets used to pound the pulp were replaced by mechanical hammers powered by animals or waterwheels. This paper revolution is one reason Al-Jazari had access to technical literature.

ס – Samech- skepticism (In Hebrew ספקנות) – Al-Jazari opens the fourth chapter—which features fountains that change shape and continuous flutes—with the brief statement that he ” I did not follow the system of the Banu Musa, may God have mercy upon them, who in earlier times distinguished themselves in the matters covered by these subjects. ” Banu Musa (Sons of Musa) is the collective name for three scholarly brothers from the ninth century, the sons of Musa ibn Shakir, an astronomer of Persian descent. Together, they authored over twenty books, though most have been lost over the centuries. Al-Jazari’s primary reservation concerns the method of control employed by the brothers. The field of control systems has evolved so dramatically that historical techniques for regulating timing now intrigue us merely as a curious puzzle. Yet, curiosity and skepticism continue to guide every good engineer today, just as they did eight hundred years ago.

ע – Ayin- Slaves (In Hebrew עבדים) “A Slave-girl holding a wine cup“- refers to an ornate wooden cabinet with two doors that stands beside the king during the banquet. Every seven and a half minutes, the doors open, and an automaton (a mechanical figure) of a slave girl appears in the opening, holding a cup full of wine in one hand and a small towel in the other. A brief search of the “Book of Knowledge of Ingenious Mechanical Devices” reveals ten different chapters mentioning male or female slaves. When I think of slaves, I think of backbreaking labor in cotton fields or on the coffee and sugar plantations of South America. The Islamic world of the twelfth century was not characterized by large-scale agricultural production; the use of slaves in households reflects the relative wealth and urban character of the Muslim elite.

Automaton of the Slave Girl, Serving a Glass of Wine”, a folio from Syria or Iraq, 1315

פ – Pe- Patents (In Hebrew פטנטים)  – The question “What did Al-Jazari invent?” occupies many writers online. His contribution to the world of engineering is immense, encompassing automata and the use of the camshaft, pioneering advancements in candle clocks (including the invention of the bayonet mount), thermal insulation, the double-acting pump, and more; yet, Al-Jazari predates the concept of patents, which would emerge in 15th-century Venice—some three hundred years after his time. At the end of the book, he writes:

” In this five chapters [it is somewhat odd—the book actually contains six sections; [I have not seen anyone address this missing section?] I have described roots which have many branches and great usefulness. When the descriptions are mastered, from them many more [things] may be created. I have omitted to mention many devices which I invented, for fear of obscurity or ambiguity. In what I have mentioned there is information for him who seeks information and profit for him who has zeal. “

It seems to me that this could serve as a manifesto for anyone who believes in the sharing of knowledge.

צ – Tzadi– Fountain Designs (In Hebrew צורת המזרקות)  – The “Book of Knowledge of Ingenious Mechanical Devices” describes six different fountains. They differ from one another in the water shapes they produce, as well as in their timing and control methods. A significant portion of Al-Jazari’s work falls into the category of “fine technology”- a term historically applied to a wide range of machines serving various purposes, such as water clocks, automata, astronomical instruments (though not by Al-Jazari), and more. Some were designed to measure time or assist in other scientific measurements, while others were intended for entertainment and amusement. What these devices all share is remarkable engineering skill and the sophisticated use of mechanisms and control systems. Although control theory relies on mathematics that Al-Jazari could not have known, the fundamental issues of control have remained the same from the 12th century to the present day.

 

ק – Kuf– Kaba (In Hebrew קאבא)  – The qaba (قابا) is a type of robe, ranging in length from the knee to the ankle, that is fastened by wrapping one side over the other. According to the illustrations in the “Book of Knowledge”, it was widely worn by everyone: slaves, free men, and even the king himself. Turbans, however, were reserved for free men. In Arab culture, the turban عمامة)) was a source of pride and a symbol of religious affiliation. The illustrations show that all free men wore beards. Growing a beard (لحية) and grooming the mustache are practices associated with Sunni Islam and are considered Fitra (فطرة‎) – the natural state in which humans were created. No image of Al-Jazari himself has survived, but one can picture him wearing a qaba and a turban, with a mustache and beard.

Enthroned person wearing a Qaba dress with tiraz armbands, Kashan, late 12th-early 13th century CE. (Wikipedia)

ר – Reish– Multi-Lock (In Hebrew רב-בריח) – In 1972, a distraught customer entered the lock shop where Avraham Bachri worked and asked him to install four locks on her door to restore the sense of security she had lost following a break-in. This simple request sparked Avraham’s imagination; together with his friend Moshe Dolev, he developed a multi-bolt lock—initially installed in a wooden door and later in a door with a steel core.” (From the Rav-Bariach website(in Hebrew)

I have no reason to suspect that either of them was aware of the multi-bolt lock designed by Al-Jazari some 800 years earlier. This fascinating parallel led me to reflect on inventions and “reinventions.” The question of who invented the telephone or the incandescent light bulb—to cite two very famous examples—usually carries legal and economic implications. For me, however, the subject is more interesting from the perspective of the human spirit.

ש – Shin– Musical Slaves (In Hebrew שפחות מוזיקליות) – The “Musical Boat” -featuring female musicians—is the fourth of ten automata (mechanical figures) and devices designed to entertain guests at banquets held in the royal court of Diyarbakir. It is a beautiful wooden boat carrying figures of the king, a cupbearer, banquet companions, and four female musicians: two tambourine players, a flutist, and a harpist. These female musicians and singers—known as Qiyān ( قِيان )—were poets, vocalists, instrumentalists, and dancers who received a broad education from a young age, encompassing the sciences, philosophy, and the arts. There is considerable information regarding the Qiyan in Baghdad, the capital of the Abbasid Caliphate. While the tiny Artuqid kingdom cannot be compared to the Abbasid Caliphate, the presence of these female musicians, alongside the region’s distinctive architecture and the initiative to compile the “Book of Knowledge of Ingenious Mechanical Devices”, suggests a flourishing culture.

ת – Tet– The Isfahan Chests (In Hebrew תיבות מאיספהאן) – In the sixth chapter (the appendix section), Al-Jazari describes a “lock for securing a chest using 12 letters of the alphabet.” None of Al-Jazari’s marvelous machines have survived the intervening centuries; all that remains are beautiful manuscripts. The David Museum in Copenhagen houses fragments of a brass chest—inlaid with silver and copper—featuring four letter-locks in a slightly different configuration, crafted by an artisan named Asturlabi from Isfahan. It bears a striking resemblance to Al-Jazari’s chest. To my astonishment, the Museum of Fine Arts in Boston holds yet another chest-safe made by Asturlabi. Why did two of Asturlabi’s chests survive while not a single machine of Al-Jazari’s did? There is—and can be—no answer to this. Yet these two chest-safes from Isfahan, Persia—dating back to the late twelfth century—offer the closest thing to time travel: a glimpse of Al-Jazari at work.

Fragments of a box made by Asturlabi, 1200 AD, Museum David Copenhagen

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What do we know about Al-Jazari? Part 2: School and Training

Al-Jazari does not write about himself except a little, as explained in Part I. There is still quite a bit we can learn about the man from the wonderful book he wrote.

The Kuttab

In the 12th century, the Kuttab (كُطَّاب) was the primary school of the Muslim world. The main purpose of the Kuttab was to teach the Quran: children, mainly boys and occasionally girls, memorized it, learned correct recitation, and acquired basic religious knowledge. The education included reading and writing, verb conjugations, and basic arithmetic, as well as skills valuable for everyday life, commerce, and administration. The emphasis was on memorization and discipline, which often included corporal punishment. Scholars estimate that 15–25% of the male population was literate. Most of them studied at the Kuttab, and wealthy and educated families hired private tutors. The poor, rural, urban, and nomadic classes did not learn to read or write at all. The Kuttab was often a small local institution, sometimes just a room attached to a mosque, a private house, or a shaded shelter under a veranda. The teachers were usually called muʿalm (معلّم). They received a low salary from the students’ families or from the waqf (وَقْف, endowment) that supported education. The students sat on mats and wrote verses from the Quran on wooden tablets that could be washed for reuse. The Kuttab was seen as much a religious duty as an educational tool.

Kuttab, from Maqamat Al-Hariri ( مقامات الحريري), 13th-century manuscript, British Library.

The Mathematical Perspective

Al-Jazari’s education and training can also be viewed from a mathematical perspective. In the 12th century, there were no secondary schools. The few who wished to, and could afford it, continued their studies with the help of private tutors. Mathematics in the Islamic world in the 12th century was a rich and mature discipline, fully integrated into the sciences, engineering, and even Muslim life. Algebra, for example, was used in inheritance law (علم الفرائض), land division, and commercial contracts. As early as the 9th century, Al-Khwarizmi (الخوارزمی) wrote the foundational book on algebra and compiled trigonometric tables. This mathematical culture later passed to Latin Europe, and parts of it became the foundations of science in the late Middle Ages and early modern period.

Let’s consider, for a moment, the elephant clock. The sinking buoy pulls a rope, which rotates a pulley about its axis. On the pulley sits a scribe that indicates the passing minutes. All this will only work if the diameter of the pulley matches the path of the sinking buoy and the length of the rope. This requires the use of geometry and relationships (proportionality). There is not a single equation in the chapter on the elephant clock. There is no use of algebra, Euclidean geometry, or trigonometry. Al-Jazari’s mathematics is not explicit but is found within the machines. Al-Jazari apparently worked by trial and error and the healthy intuition of a craftsman.

A Soviet stamp commemorating the Persian mathematician and astronomer Muhammad ibn Musa al-Khwarizmi

The mathematical background, or rather the lack thereof, supports the claim that Al-Jazari studied in the Kuttab and nothing more.

Apprenticeship

An apprentice is a young person who learns a profession or craft through an apprenticeship with a skilled craftsman, a Master. As part of the apprenticeship, the apprentice serves as an assistant to the craftsman and sometimes even as a servant. In the Middle Ages, throughout the Muslim world, in Christian Europe, and beyond, this was the royal road to learning blacksmithing and metal work, and it is very likely that Al-Jazari studied with such a Master as an apprentice.

Guilds were a central part of the social structure in medieval Western Europe. The entry into a guild was through apprenticeship. After several years of training, the apprentice was qualified as a “journeyman,” a craftsman whose training was complete but who was not yet able to set up his own workshop. The journeyman found their livelihood by working for a daily wage for another craftsman, and by moving among various craftsmen, they helped spread new knowledge and techniques. After several years of work, travel, and experience, a journeyman could be ordained to the rank of a “Master”. We have countless European documents on the subject of guilds and training, including contracts signed between apprentices’ parents and the master who took them under their protection. In contrast, in the Muslim world, apart from a few apprenticeship contracts in the Cairo Genizah, there are no apprenticeship contracts at all; there is no historical evidence for the existence of craft guilds, and there is not even an Arabic term for them. Ultimately, it was Goitein (Shlomo Dov Goitein, the central historian in the study of the Cairo Genizah) who rejected this outright: “There was no such term because guilds in the narrow sense of the word had not yet arisen.”

The historical differences between Western Europe and Islamic countries had little if any effect on the daily life of the apprentice. The vast majority of students who completed the Kuttab, as well as those who did not receive primary education, received vocational training. Children joined their parents in agricultural or urban work or as apprentices to professionals in the workshops of the markets. Even in the absence of written contracts, training began between the ages of 10 and 14. The agreement, even if oral, stipulated that the artisan was obliged to teach the boy his craft (صناعة). Although some of the contracts in the Cairo Geniza are for only a few months. It is clear that no one learns blacksmithing or any other metalworking technique in a few months. In Western Europe, where records exist, the apprenticeship lasted 7 years, and it is likely that this was also the case in Muslim countries. These contracts also specified the master’s duties (training, food, lodging, and often clothing). And the duties of the apprentice with an emphasis on behavioral requirements: the apprentices had to be obedient, loyal, and not “degrade” the workshop. In the Muslim world, these were oral agreements based on Muslim law. Al-Jazari is a very skilled craftsman, and the book is full of details that demonstrate his intimate knowledge of metalworking. For example, when he explains how to make the main water tank for the castle clock, he does not content himself with a drawing and the choice of materials (copper) but details how to obtain a perfect cylinder using a precise wooden disc and how to ensure that the cylinder is the same in diameter throughout. Al-Jazari makes extensive use of iron, copper, bronze, and lead, as well as a variety of processing techniques, such as hammering, casting, and soldering. In the Middle Ages, there was no other way to learn metalworking than through apprenticeship.

Medieval blacksmith at work, 14th century Sloane Manuscript No. 3983, British Library

Al-Jazari – Professional Literature

Al-Jazari’s approach to the professional literature of his time is impressive. In the post on the castle clock, we saw that Al-Jazari knew and criticized the work of Archimedes, and in the post on the fountain with two tipping buckets, we discussed his dispute with the Banu Musa, but the highlight is in the chapter on the perpetual flute, where he cites three sources:

 “I came across a well-known paper by Apollonius, the Indian carpenter: he made a wheel which turns slowly and opens water outlets…”

“I also examined another old instrument, about which I found no written report, but a drawing. In this, the flute is like a nay having eight holes”.

“I [also] examined a paper written in Baghdad in the year 517 A.H. by the eminent inventor Hibat Allah al-Husayn al-Asturlibl, in which he makes a real innovation….

During my time as a teacher at the Davidson Institute for Science Education and in academia, I have seen how difficult it is for students to read an article critically. The fact that Al-Jazari does this regularly is impressive and tells us something about the man.

Mechanical treatises were relatively rare, certainly compared to manuscripts in medicine, theology, or law. The previous important book is by the Banu Musa and contains no such references to earlier sources. In this respect, Al-Jazari is truly groundbreaking, bringing engineering literature closer to classical knowledge. This is all the more surprising since the Banu Musa brothers were educated at the House of Wisdom, a magnificent institution in the heart of Baghdad with a very broad mathematical and scientific education, and Al-Jazari studied only the Kuttab.

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What do we know about Al-Jazari? Part A

We have no information about Al-Jazari’s life except what he wrote himself in the introduction to his wonderful book (Hill’s translation):

” I am in the service of the king al-Salah Nasir al-Din Abi al-Fath Mahmud bin Muhammad bin Qara Arslan bin Dawud ibn Sukman bin Artuq, the king of Diyar Bakr, may God preserve him with those whom He chooses to preserve. That is following my service to his father and his brother, God sanctify their souls, before the kingship passed to him – a [total] period of twenty-five years, the first of them year 577 [Hijri- 1181 AD]. God, may He be exalted, has singled him out with distinctions of intelligence, high-mindedness, justice, and probity, so that he surpasses in justice and probity the kings of the present age, and excels the lords of near and far in beneficence and graciousness.”

In many places, it is claimed that Al-Jazari was born in 1136 and died in 1206. As for his birth, I have not found any historical source, and I fear that this is a complete fabrication. As for his death, we can use the colophon of manuscript number 3472 in the Topkapi Library, the earliest copy of the Book of Knowledge of Ingenious Mechanical Devices. The colophon is a note by the scribe, usually at the end of the manuscript, in which the scribe records details about its creation, such as the date, place, their name, the book’s title, etc. The colophon consists of two parts.

The first part is the testimony (شهادة):

“Its correctness has been attested to, and this book was collated against the handwriting of its author, Badiʿ al-Zamān Abū al-ʿIzz Ismāʿīl ibn al-Razzāz al-Jazarī — may God have mercy upon him.”

The testimony does not state the year of Al-Jazari’s death, but the reference to Al-Jazari (“May Allah Almighty have mercy on him” (رحمه الله تعالى)) is a typical one for someone who has already passed away.

The second part is a classical colophon:

“Praise be to God, Lord of the Worlds, and blessings and peace be upon our master Muḥammad, his family, and companions all together. The completion of the manuscript occurred on 12 Shaʿbān[The eighth month of the Muslim year] 602 A.H.[ [Hijri- 1206 AD]. It was written by the humble servant in need of God’s mercy, Muḥammad b. Yūsuf b. Uthmān al-Ḥaskafī—may God forgive him and all Muslims.”

The book was written in 1206 AD. This is based on the book’s introduction quoted above. Al-Jazari began his work in the palace in 1181 CE and worked there for 25 years. If so, he probably died a few months after completing the book.

When I discovered the Book of Knowledge of Ingenious Mechanical Devices, I looked for additional historical sources on Al-Jazari and his machines, such as a Muslim traveler who passed through Diyarbakir and testified to the machines he saw with his own eyes. Or perhaps a historian or biographer of Muslim scholars who would expand on the limited information from the book’s introduction. I wanted to learn more about the engineer who wrote the book I loved. This is probably naive, although there are still many Arabic manuscripts that have not been translated, or even cataloged, and no one knows what is written there.

During my research, I found famous travelers like Ibn Jubayr (ابن جبير), who left Mosul in June 1184, on his way to Damascus. He passed through the southern outskirts of the Artuqid principality. Ibn Battuta (ابن بطوطة) visited Mardin (ماردين) in 1326 and other places. Also, less well-known travelers such as Abu al-Hasan al-Harawi (أبو الحسان الهروي), who visited the area in 1215, a few years after the death of al-Jazari, and Ibn Shaddad (عز الدين بن شدداد), who wrote extensively about Diyar Bakr. I have written here about Ibn Jubayr’s Travels and Ibn Battuta’s [in Hebrew] Travels. In neither book is there a word about al-Jazari or his machines.

The travelers focused on geography, particularly holy places such as Mecca and Jerusalem. They also dealt extensively with Muslim issues, such as prayer times, mosques, Waqf (وَقْف), and covered political order, including rulers, justice, and security for the inhabitants. They described social customs such as clothing, markets, and food, and sometimes gender norms as well. There are a few reports of wonders (عجائب), but these are mainly natural wonders, such as the tar springs near the Tigris. To the best of my knowledge, there is no one description of clocks or other mechanisms. This is also true of Christian travelers in Western Europe during the Middle Ages. Al-Jazari’s absence from the travel books has more to do with the genre than with him and his machines.

I am more surprised by the complete silence of medieval historical sources. Ali ibn al-Athir al-Jazri (علي بن الاثیر الجزری) was a historian, hadith scholar, and biographer of great importance. His name ends in al-Jazri (الجزری), like the author of our book. The suffix of the name (نسبة in Arabic) indicates the place of origin of the person, his ancestral tribe, or his ancestral origin. In this case, it is the city of Cizre in Turkish Kurdistan, near the Turkey-Iraq-Syria border triangle. Its ancient name is Jazira Ibn Umar (جَزِيْرَة ٱبْن عُمَر). We have a wealth of information about Al-Jazari the biographer, unlike Al-Jazari the engineer, and we know that he was born in Cizre on May 12, 1160 AD. Was Al-Jazari, the engineer, also a Cizre native, or is it just his family’s origin, even though he was born in Diyarbakir? We will probably never know. Either way, al-Athir was a major historian in the Middle Ages, and his book “The Complete History” (الكامل في التارخ) is a seminal historical source to this day. There is no mention of Al-Jazari the Engineer. One could argue that this is due to the book’s organization, which presents a comprehensive, chronological world history, extending from the creation to the time of the Prophet to the time of Ibn al-Athir, with scholars appearing only in the context of a significant contribution to a noteworthy event. But al-Jazari does not appear in the writings of Yaqut al-Hamawi (ياقوت الحَمَوي) or Ahmad ibn Khalkan (أحمد ابن خلكان). The latter was a renowned historian who wrote the famous biographical encyclopedia of Muslim scholars and is considered the most prominent biographer in Islamic history. This silence is especially striking, since Ibn Khalkan lived in Erbil and Damascus, not far from Diyarbakir, in the very same century.

How can this be explained? Humanity needed engineers in ancient times; the Pyramid of Giza or the Aemilius Bridge in Rome were not built without the involvement of someone who is today called an engineer. But unlike philosophers, doctors, or religious scholars, an engineer was not considered a scholar but a skilled craftsman, however talented, and Al-Jazari, although highly respected among his Artuqid patrons, was also seen as an artisan, a craftsman. His legacy survived through his book, not through mentions in chronicles or biographies. It was only in the modern period (19th-20th century), with scholars such as Wiedemann, Hauser, and later Donald Hill, that he was “rediscovered” as a central figure in the history of technology.

All that remains is to turn to the book of Ingenious Mechanical Devices to learn about Al-Jazari, the man, and you can learn quite a bit. Some insights about Al-Jazari are scattered across the blog’s posts. In Part B, I have compiled them into a portrait of the man that emerges from his book.

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The Elephant Clock – A Question of Energy

Introduction

The concept of energy in physics can be confusing because it is not a tangible “thing,” but rather an abstract physical quantity that represents the ability of a system to do work. According to the law of conservation of energy formulated by the German physician and physicist Hermann von Helmholtz, energy cannot “disappear” or be created out of thin air but can only be transferred from one body to another and take on different forms. The fact that we use “energy” in everyday life in sentences like “I woke up this morning full of energy” or “She has positive energy” that have little or no connection to the physical concept only makes it difficult for students. To complicate things further, energy has many different units. I will do all the calculations below in joules, denoted j. A joule is a unit of energy in the MKS (meter-kilogram-second) system. One joule can be used to lift a relatively small apple one meter high, or to heat a gram of water by about 0.24 degrees Celsius. It is also the energy needed to light a one-watt light bulb for one second. In other words, it is a small amount of energy.

Every clock has a source of energy. When I was a child, wristwatches were mechanical and, in the evening, you would wind their spring. My father had an “automatic” wristwatch that seemed to me a technological marvel; the movement of the hand powered a rotor (a metal weight that wound the spring). My beloved had three cuckoo clocks in her grandfather’s apartment. At the foot of the coop was a balcony with loving couples. Every hour, a song was played, the balcony spun, and the couples spun within it, and when silence returned, everyone stood from their dance until the next hour. The energy for the clock was provided by pinecone-shaped weights that slowly descended. Once a day, they had to be raised again by pulling a chain. Today, wristwatches and wall clocks, if they are still used, are mostly electronic clocks based on the oscillations of the quartz crystal to display the passing time, so their energy source is an electric battery.

Lego Elephant Clock – Energy Calculations

The (original) elephant is made of copper, and partitions were installed in its belly, making it a hidden water reservoir. Lego is not waterproof, so there is a container made of transparent plexiglass (acrylic glass) in the elephant’s belly. A float with a hole (طرجهار) was placed in the reservoir, which slowly sank. In Al-Jazari’s case, this took half an hour. Considering the patience of modern viewers, I shortened the sinking time to five minutes.

Either way, when the float has finished sinking, its chain pulls the moving channel. This causes a metal ball to roll into its path, and a new ball takes its place. The ball falls into the dragon’s gaping mouth. The extra weight causes the dragon to swing on its axis and pull the float back to the water surface. The clock’s energy source is therefore the metal balls that a servant positions at the top of the clock at dawn. In this post, I will present the fixed and moving channel mechanism, as explained in “The Book of Knowledge of Ingenious Mechanical Devices”, my modern version, and also provide the energy calculations of the clock. This is the image of the Lego elephant with the ball channel area marked with a red circle, and also the heights of the steel ball at various locations, which will be used for the energy calculations later:

Lego Elephant Clock 2025

The ball channel mechanism in “The Book of Knowledge of Ingenious Mechanical Devices

The mechanism of the ball channels is described in subsection nine and is simple to understand. This is a drawing from the book:

The L-shaped channel is the fixed channel, and although the drawing shows only five balls, the clock had 29 balls intended for 14.5 hours of light at the height of summer, with one ball falling every half hour. The balls were made of bronze; this is not explicitly stated, but there is an identical mechanism in the water clock of the boat, and it is explicitly stated there that the balls are made of bronze and weigh 30 dirhams, approximately 90 grams.

Bronze is an alloy of copper and tin, and its density varies with composition. Assuming 8.5 g/cm3 these were balls of about 10 cm3 with a diameter of a little more than 2.7 cm. The balls I used are stainless steel, have a very similar density, and weigh 56 grams. The fixed channel is inclined so that the metal balls roll down to the moving channel. The latter is on the opposite slope and an axis. When the float pulls down the channel, the metal ball rolls away, and a new ball takes its place. This is a top view of the fixed channel and the moving channel.

A top view of the fixed channel and the moving channel in the Lego Elephant Clock.

Attached is a short video showing how the ball channels work:

Energy Calculations

The height of the ball relative to its final position is shown in the image above. The potential energy Ep is given by:

Ep =mgh

Where m is the mass of the ball, 0.056 kg

g is the free fall acceleration due to gravity and is equal to 9.81 m/s2

h is the height relative to the reference plane. At the starting point 0.95 m.

The energy available to us is:

Ep=0.056*9.81*0.95=0.52 j

Joule, as you may recall, is the unit of energy in MKS units and is explained shortly in the introduction. In Al-Jazari’s time, the concept of energy did not exist, of course, and in general, Al-Jazari makes few calculations and works mainly by trial and error. Can energy calculations be helpful to us? The fall of the ball provides energy to all parts of the clock, from the rotation of the bird to the operation of the mahout (elephant trainer and driver). The most essential part is raising the float to the surface of the water. At the beginning of the process, the ball is in the dragon’s mouth at the height of the castle, and the float is filled with water. At the end of the process, the float was lifted and turned over, and the dragon unloaded the ball above the vases. This is a drawing of the process:

Drawing the Dragon’s Rotation Process

I will discuss the physics of the buoy’s inversion process in detail in a future post that will focus on the dragon and its spectacular rotation. What can we learn from simple energy considerations?

The energy required to invert the buoy EFF is given by:

EFF =(mw+mf )*g*∆h

mw is the mass of the water in the buoy, about 140 grams = 0.14 kg

mf is the mass of the buoy, about 48 grams = 0.048 kg

g is the free fall acceleration, equal to 9.81 m/s2

∆h is the height difference between the submerged buoy and the inverted buoy above the water, approximately 10 cm = 0.1 m. The energy required:

EFF=0.19*9.8*0.1=0.19 j

The energy available for the water clock:

Ep=mg*∆h

Where m is the mass of the stainless-steel ball, 0.056 kg

g is the free fall acceleration, equal to 9.81 m/s2

∆h is the difference in heights. The ball rolls into the dragon’s mouth at a height of 0.8 m and is released above the jugs at a height of 0.3 m. The difference is:

∆h=0.8-0.3=0.5 m

The energy available to us:

Ep=0.056*9.81*0.5=0.27 j

So there is enough energy to turn the float.

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The Elephant Clock is back! The Wheel of Hours

Warning! This post, like the upcoming ones, will be filled with technical jargon and details that may be of interest to enthusiasts of 12th-century technology. Apologies to readers who see Al-Jazari as a window into 12th-century culture.

Introduction

Six years ago, when I started working on the Lego elephant clock, I wrote:

“The elephant is in the initial stages, and I hope to post an update every week. I’d love to hear your suggestions, ideas, or advice you may have for me.” You can read the original post here.

In the meantime, I earned a bachelor’s degree in Arabic and also returned to teaching at Davidson; however, all these distractions prevented any real progress. Now, I am working on it continuously, and this is what the elephant looks like now.

Lego Elephant Clock 2025

The ambition to design the elephant clock purely from Lego proved unrealistic. The elephant itself and some of the delicate mechanics are from Lego. Still, many mechanisms were redesigned, based on the descriptions in al-Jazari’s book, using CAD software (Fusion 360) and printed on a 3D printer (FlashForge Inventor Dual Extruder).

How does the elephant clock work?

The elephant clock features eight distinct mechanisms with intricate interrelationships. They will be described briefly here. A detailed post will be dedicated to each one. I will translate al-Jazari’s text and explain my modern interpretation. I will discuss what works and what doesn’t. I would be delighted to receive questions, comments, or suggestions for improvements. If you have any suggestions, I promise to try them and report back on what happens, as well as any progress made.

  1. The (original) elephant is made of copper. Partitions were installed in its belly, and it became a hidden water reservoir. A float with a hole(طرجهار)    was placed in that reservoir and slowly sank. This is the core of time measurement. In Al-Jazari’s book, the sinking time is half an hour.
  2. On the float rests a weight attached to a pulley. On the pulley’s axis sits a scribe holding a pen. When the float sinks, the weight sinks with it, causing the scribe to rotate and its pen to indicate the passing minutes.
  3. The clock’s energy source is metal balls stored in the ball channels. The height difference enables the clock’s cyclical operation. After half an hour, when the float has finished sinking, the chain pulls the channel. This causes a metal ball to roll down and start its journey, and a new ball takes its place.
  4. The ball falls on a wheel of slanting blades attached to the bird and causes the bird to rotate.
  5. The Circle of Hours – This is the heart of this post. The purpose of the circle is to show the passing of time. Above the Falconer are fifteen round windows. At sunrise, all the windows are darkened. Every half hour, half of a window becomes silver color. So, the number of silvered windows represents the hours that have passed. This mechanism is explained in full below.
  6. The ball falls from the wheel of slanting blades area to the “selector” mechanism, which chooses whether the ball will fall once to the right dragon and once to the left dragon, and accordingly tilts the Falconer. I couldn’t find a solution in Lego for the Falcon heads, and therefore, the balls come out of a simple opening.
  7. The ball falls into the dragon‘s gaping mouth. The extra weight causes the dragon to flip and pull the float back to the surface of the water. When the dragon reaches the bottom, it releases the ball into the vases that lead to the mahout (elephant rider and trainer) mechanism.
  8. From the vases, the ball rolls through pipes to the mahout It falls onto a swing that is attached to the mahout’s arms, causing the mahout to hit the elephant’s back with a hammer and a mallet.

The mechanism of the wheel of hours

The text is the English translation by Dr. Donald Hill. I slightly modified the original text.

“One takes a fine ring of silver, its diameter the same as the diameter of the circle of holes, its width the same as the diameter of one hole, and a little more than that. For half of it, the silver is blacked over. Then, a copper disc of the same diameter is laid on the back of the silver ring and firmly soldered to it.

An axle is fitted to the center of the disc, which does not penetrate the face of the castle. The ring now covers the holes, and when it rotates, it does so with ease.

Then, on the perimeter of the disc, 30 teeth are fitted at right angles to the circumference. Each tooth has the shape and the length of a barleycorn, and they are equidistant from one another.

Let the black half cover the holes, the white half being underneath. Now, two links are taken and connected by a pin to form a hinge in such a way that when one rotates about the other, there is no restriction in one direction, but in the other direction, it cannot rotate and remains colinear. One link is longer than the other. In the longer link, an axle is fitted crosswise, near the hinge pin, on the inflexible side:

Fig. 57 The Book of Knowledge of Ingenious Mechanical Devices translated and annotated by Dr. Donald Hill

On the longer link is a و, on the shorter an ه, and on the two ends of the axle م م

Then, the end of the short link is placed between the first and second teeth of the disc, and the end of the long link is beneath the end of the moving channel. The ends of the axle are placed in two firm bearings, one in the right-hand plate of the castle, the other on a crossbeam which does not impede the movement. The flexible side is uppermost, and the non-flexible side is underneath. Now, I say that when the ring at the end of the moving channel is pulled down a set distance, it is prevented from descending below the set distance. Then, the end of the channel forces down the end of the long link و , which descends by a known distance, while the end of the short link ه rises by a known distance. Therefore, the tooth at the end of the short link rises by a known distance – namely half the diameter of a hole. The disc moves, and the white part of the ring rotates over half the first hole. When the moving channel returns to its position, its end lifts from the end of the long link, that light end rises, and the end with the pin in it descends. This end is weighted with lead and, therefore, sinks due to its weight. The short link comes out from between the first and second teeth and enters between the second and third. This happens every time the ring at the end of the moving channel is pulled.”

Fig 58.The Book of Knowledge of Ingenious Mechanical Devices translated and annotated by Dr. Donald Hill.

The Circle of Hours – The Lego Elephant

The round holes are replaced with transparent Lego blocks:

The facade of the castle from the manuscript (Topkapi 1206) compared to the facade of the castle from the Lego elephant

Al-Jazari’s disk with the silver ring has been replaced with a 3D-printed disc. In different manuscripts, the shape of the teeth that Al-Jazari describes as “barley grain” is different. The drawing below is a comparison between the printed disk and a drawing from a 17th-century manuscript of the book:

The lever that is supposed to rotate the hour wheel one tooth at a time looks like this:

The front can rotate freely, as shown in the photo:

In the front link, three lead balls weigh about 0.4 grams. This is enough to cause it to fall unless something pushes it upwards, but this does not happen during regular operations. To clarify the problem, a short video is attached:

You can see that when the end of the long link goes down, the end of the short link goes up as al-Jazari planned. The short link pushes the tooth, the hour circle rotates, and the silver half-ring covers the first transparent brick. But when you let go of the end of the long link, it rises, and the short (heavy) link sinks, but contrary to what is written, it does not come out between the first and second teeth but gets stuck in the second tooth and pushes it back down in the opposite direction of rotation?

I’m unsure whether there’s a problem with al-Jazari’s original design or with my implementation, and I would appreciate any suggestions or assistance.

 

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Ibn Jubayr and the Artuqids Principality

Introduction

Since I came across al-Jazari’s book, I have been hoping to find a Muslim traveler from the 12th or 13th century who visited the Artuqids’ court and saw with his own eyes the elephant clock and other wonderful machines built by al-Jazari. This is probably a childish fantasy, although there are still many Arabic manuscripts that have not been translated or even cataloged, and no one knows what is written within them.

As I have written before, we are aware of three books that originated from this tiny principality: Al-Jazari’s book, which is the reason for this Blog. A few years before that, Usama ibn Munqidh((أسامة بن منقذ) wrote his book ” The Book of Contemplation  (كتاب الاعتبار), and there is also a third, lesser-known book by al-Jawbarī (الجوبري) called ” The Book of Charlatans ” (كتاب المختار في كشف الأسرار). Three books that have come down to us from a tiny principality in Anatolia represent only a part of the cultural flowering during the Artuqids period. Can we learn anything about the Artuqidss and the principality from travelers who visited it or were nearby?

During my research, I found very famous travelers, such as Ibn Jubayr, who left Mosul in June 1184 on his way to Damascus via Aleppo. He passed through the southern outskirts of the Artuqids principality. In 1326, Ibn Battuta (ابن بطوطة) visited Mardin (ماردين) and other places. In this post, I will focus on Ibn Jubayr, and later, I may write about Ibn Battuta and other travelers I have identified, such as Nasir Khusraw (ناصر خسرو), who was in Diyar Bakr (ديار بكر) in 1046, when it was still ruled by the Marwanids (مروانيون). Abu al-Hasan al-Harwi (أبو الحسان الهروي), who visited the area in 1215, and Ibn Shaddad (عز الدين بن شدداد ), who wrote extensively about Diyar Bakr. This is a map of this part of Ibn Jubayr’s journey:

Map of the Artuqids principality, with the approximate borders marked in black and Ibn Jubayr’s route in green.

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Ibn Jubayr’s travels in the Artuqids principality

Abu al-Hasan Muhammad ibn Ahmad ibn Jubayr (أبو الحسين محمد بن أحمد بن جبير) was born in 1145 in Valencia, died in 1217 in Alexandria, Egypt. He is known for a book documenting his pilgrimage to Mecca that began in 1183 and ended with his return to Granada in 1185. He wrote a vivid account of this journey in his book “The Travels of Ibn Jubayr (رحلة ابن جبير).” In 580 AH or 1184 CE, he arrived at Nasibin, a town in Upper Mesopotamia, now called Nusaybin in modern Turkey. This is an ancient city mentioned as early as the Assyrian period. In the 12th century, it changed hands many times and was briefly conquered by Ilghazi ibn Artuq (إيلغازي بن أرتق), who ruled Mardin from 1107 to 1122. Ibn Jubayr only passed through the southern outskirts of the principality a few years after al-Jazari began his service at the royal court. It is quite possible that al-Jazari’s monumental works had not yet been completed or that ibn Jubayr did not hear about them. One can still be impressed by Nasibin’s poetic description.

” Renowned for its age and its past, outwardly fresh but decrepit within, beautiful to look upon and of medium size, it stands in a verdant plain which stretches before and behind it is as far as the eye can reach. In this plain, Allah has made to run streams of water that irrigate it and flow in all its parts. The city is begirt with gardens, thick with trees bearing ripe fruits, and round it there bends, like a bracelet, a river with its banks beset with the gardens that cover it with their ample shade. God’s mercy upon Abu Nuwas al-Hassan ibn Hani (أبو نواس –The Father of Curls. The court poet of Caliph Harun al-Rashid, considered by many to be one of the greatest Arab poets of all time) said:

“Nasibin was pleased with me one day

And I was pleased with it. Oh, that my lot in this world were Nasibin.”

Ibn Jubayr continues to describe the city and the stream that enters the town, passes through the streets, and reaches the mosque, where it flows into two basins: one in the center of the mosque and the other near the eastern gate, which in turn reaches two fountains. This description is particularly interesting because al-Jazari describes in his book designs for six fountains that change their shape. All of al-Jazari’s fountains have a time-based control system. Today, it is trivial to control a fountain using an electronic control system. Still, in the 12th century, it was a significant engineering challenge, and al-Jazari proposed a variety of elegant solutions. A water source, such as the stream that Ibn Jubayr describes, and a water collection basin and a fountain are the components from which al-Jazari built his elaborate fountains, and the text demonstrates their availability.

The fountain with two tipping buckets, Topkapi manuscript, 1206

The fountain with two tipping buckets, Topkapi manuscript, 1206

In the following paragraph, Ibn Jubayr speaks of the rulers of the Nasibin Mu’in al-Din (معين الدين), the brother of Mu’izz al-Din (معز الدين), the ruler of Mosul. The rulers of Mosul in the 12th century were from the Zangid dynasty (الدولة الزنکية). Like the Artuqids, they are a Turkoman dynasty from the Oghuz tribes (ٱغُز) that ruled parts of the Middle East, including Mesopotamia, with varying degrees of independence from the Seljuk Empire.

The 1180s were politically complicated by Saladin’s pressure on local rulers in Greater Syria and Mesopotamia, including the capture of Aleppo in 1183, the capture of Diyarbakir in 1185, and a failed attempt to capture Mosul. The local princes ruled at his desire and, to a large extent, became his vassals. The Artuqids did not control Nasibin in 1184, which indicates the small size of the principality.

After meeting with a righteous sheikh named Abu al-Yaqzan (أبو اليقضان), Ibn Jubayr continues to Dunaysir (دنيصر). Today, medieval ruins remain 20 km southwest of Mardin on a tributary of the Khabur (خابور ) River. Dunaysar is not considered an important place in Islam and was never fortified. Its prosperity under the Artuqids is reflected in the remains of mosques and madrasahs. Here, too, Ibn Jubayr describes:

“This city lies in a wide plain and is surrounded by gardens of aromatic plants and green vegetables that are irrigated by means of water wheels (ساقية). It inclines to the character of the desert and has no walls. Filled with people, it has crowded markets and a wide range of commodities, being the emporium of the people of Syria, Dyar baker, Amid of the Rumi lands that give allegiance to the Emir Mas’ud. It has wide tillage and many conveniences.”

I don’t know why he mentions Diyarbakır (دير بكر) and Amid (آمد) separately. As far as I understand, Amid is the ancient name of Diyarbakır. It is interesting to note the water wheel (ساقية), the most efficient device for raising water, which was used until the introduction of motorized pumps. This is a mechanical device that utilizes a belt of buckets or jugs, powered by a vertical wheel connected to a horizontal wheel, which is driven by animals (oxen or donkeys). In Al-Jazari’s book, there are five water pumps or in Al-Jazari’s words: ” machines for raising water from pools, and from wells which are not deep, and from a running stream,” and one of them is a strange water wheel powered by a scoop wheel and a set of gear wheels but has a wooden fake cow. More on the fake cow riddle here.

Ibn Jubayr then tells us that the ruler of the city is Qutb al-Din (قتب الدين), who also rules Mardin (ماردين), Dari (داري), and Ras al-Ain (راس العين), and is a relative of the Zengid who ruled Mosul and Nasibin. He is referring to Qutb al-Din Ilghazi II (قطب الدين إيلغازي II), who ruled Mardin between the years 1176-1184 and even left us coins with his image:

Dirham Qutb al-Din Ilghazi II

Ibn Jubayr’s following paragraph is unusual and highly critical of Muslim rulers, except for Saladin. To understand it, one must know that names in Arabic have meanings: Saladin is Ṣalāḥ al-Dīn “a-Din” (the “L” is not pronounced) is “the religion” and “salah” means righteousness, good, decency, and honesty, so that the name of the Ayyubid general Saladin means “righteousness of the religion.” The meaning of the name “Qutb al-Din” is “the leader of religion,” and so on.

“These countries are subject to various rulers, after the fashion of the kings of the Arab nations in Spain. All these rulers embellish themselves with titles connected with religion(Din), and you will hear only awesome by-names and appellations that, for wise, are without profit. In this, the subject and the kings are the same, and the rich share this habit with the poor. Not one of them is known by a cognomen that fits him or is described by an epithet of which he is worthy. Not on save Ṣalāḥ al-Dīn, Lord of Syria, the Hejaz, and the Yemen, and famous for his virtue and justness”.

The second category of Al-Jazari’s book is devoted to:” On the construction of vessels and figures suitable for a drinking session. This chapter contains ten amusing inventions for drinking parties. For example, the automaton (mechanical doll) that drinks the king’s leaving. This is clear evidence that the Artuqid court in Diyar Bakr lived in peace with alcohol. There are plenty of references to Islam and its customs in the book, and at the same time, feasts full of play and amusement take place without any apology or concealment. Is it this duality that led to Ibn Jubayr’s outburst?

Ibn Jubayr continued south to Ras al-Ayn (رأس العين), still part of the Artuqid principality. I did not find any helpful information about the Artuqids there, but the description is so captivating that I have quoted it verbatim:

“This name (رأس العين=The head of the spring) is a most fitting designation, and in this place are the most excellent properties, may Allah be exalted has given vent to springs in its ground that pour forth fresh water. They divide into branches and flow in channels spread through the green meadows like stripes of silver stretching across a sheet of emerald, beset with trees and gardens that are disposed along their banks till the end of their cultivated valleys. Of these springs, two are the most copious, and one is situated higher than the other. The higher rises from the ground

between hard stones that form something like the hollow of a cave, large and capacious, in which the water rises until it becomes a vast cistern. The water then pours forth like one of the greatest rivers until it comes to the other spring. This second spring is one of the most wonderful of the creations of the great and glorious Allah. It rises from a hard stone at a depth of about four men’s statures below the ground, but the spring has opened out a cistern of that depth. Sometimes, a stout swimmer and a strong diver try to reach the bottom, but the water, so strong is the spring, repels him so that he does not reach half the depth and sometimes even less. This we saw with our own eyes. The water is clearer than pure water and sweeter than the spring of Salsabil [a spring in Paradise mentioned in the Quran] and leaves visible all that is in it. If a dinar is thrown into it on a dark night, it will not be hidden.”

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Additional boxes with combination locks

Foreword

One of the best pleasures of maintaining such a blog is the emails I receive occasionally that expose me to information I am not familiar with. This time on three boxes with combination locks quite similar to the combination lock designed by al-Jazari:

The box from the Khalili Collection (ناصر خليلي)

The box from the Basilica of St. Servius in Maastricht (Netherlands)

Al Baghdadi’s box (البغدادي)

The Box from the Khalili Collection

Bernard Gallagher drew my attention to the connection he found between Leonardo da Vinci’s famous Annunciation painting and al-Jazari’s machines:

To the best of my knowledge, there is no translation of al-Jazari into Latin. I am not familiar with al-Jazari knowledge in the West before the groundbreaking work of Eilhard Wiedemann and Fritz Hauser in 1915. It is impossible, of course, to know whether an Arabic manuscript ended in Leonardo’s hands. You can read for yourself Bernard Gallagher and be convinced (or not). But during my search due to  Bernard’s ideas, I discovered this box in the Khalili collection:

Sir Nasser David Khalili (ناصر داوود خل یلی) is a British-Iranian scholar, collector, and philanthropist who, starting in 1970, has built one of the richest private art collections in the world, documented in 36 volumes that can be seen here and includes ancient manuscripts from the 4th century BC in Aramaic from Bactariya, present-day eastern Afghanistan, to Japanese artifacts from the 19th century. An important part of the collection is Islamic artifacts, including the box, between 700-2000. In volume 12, “Science, Tools & Magic Part Two: Mundane Worlds” I found information about the casket. Unlike the boxes from Isfahan (which appear in the original post), this box is neither signed nor dated. It is cast in brass and inlaid with silver. Based on the metalwork, it can be assumed that the casket was made in Jazira between the mid-13th and 14th centuries. Like al-Jazari’s box, it has four dials with 16 letters, and the correct choice of letters allows the lid to be opened. As with al-Jazri, the 16 letters used do not need diacritic marks, such as ب (ba) or ن (nun), with only the dot’s position distinguishing between the letters. The locking mechanism is simpler than al-Jazari’s (true for all three boxes) and includes only four letters compared to al-Jazari’s chest, where twelve letters are required (Detailed explanation in the original post). There are no photographs of the mechanism in the book, and if I will obtain them in the future, I will be happy to make a more detailed comparison.

Al-Baghdadi’s (البغدادي) Box from Mosul

The Khalili Collection book mentions the two boxes from Isfahan and an anonymous box from New York. I couldn’t find the box from New York, but during my search, I found this box from Mosul, which was sold at Christie’s auction house in 2010:

It is a brass box with silver inlays mostly removed with a scalpel; the silver remained only in the lock area and in places that were difficult to remove. In addition to the geometric decorations, there are hunting scenes, a figure on a camel, and much more. On the box, there is an inscription. This is the only photograph I have found, but if I understand correctly, there are two types of inscription on the box: one in the letter Naskh (خط ألنسخ ), a small round script in Arabic calligraphy. The second is Kufic (خط كوفي), the oldest calligraphic form of the Arabic script. The text includes proverbs such as الماجد والملك, meaning splendor and rule, as well as the name of the artist who made the box, Mohammed al-Baghdadi.

This box also has a similar but simple version of the lock of al-Jazari, with four dials placed at the four corners of the lid. When the combination of dials includes the correct four letters, you can lift the cover by turning the handle in the center. If I understood correctly, the mechanism was preserved in this box, but the letters that were apparently engraved on the silver inlay are missing.

The Box in the Basilica of St. Servius

Almost the same week, Danielle Arvanitis wrote to me about an ivory box she saw in the Basilica of Saint Servatius in Maastricht (Netherlands):

According to the legend, Saint Servatius, a distant relative of Jesus, was an Armenian from the 4th century AD who arrived in the city of Maastricht and became the first bishop of the Netherlands. There is evidence of pilgrimages to the basilica as early as the 6th century AD, and historical figures such as Charlemagne, Henry II, and others made pilgrimages to the saint’s remains found in a magnificent coffin belonging to the basilica’s treasury. In addition to the remains, the treasure has unique artifacts, including a spectacular collection of ancient silk fabrics, ostrich eggs, and this box.

I have found no scientific papers discussing the box other than a 1985 article by J. Klamt in German, whose charming title “Elfenbeintasten mit Kombinationsschloss” means “combination locks and ivory keys.” According to the picture’s caption, the box’s origin is in Sicily from the 13th century. I am grateful for all the information I can find on the WEB. Still, materials that do not undergo scientific review are questionable, so this may be inaccurate.

The Emirate of Sicily was a Muslim kingdom with Palermo as its capital from 831 to 1091 AD. In 826, a Byzantine general named Euphemius defected, allied with the Aghlabids ruler (Arabic: أغالبة, a dynasty of Muslim emirs who ruled over a North African kingdom), and transferred to the Muslim navy the technique of “Greek fire,” a very dangerous incendiary weapon used by the Byzantine to set enemy ships on fire, This story warrants a separate post because the process of preparing Greek fire was kept very secret,  And to this day we do not know for sure what its components were.

Either way, under Muslim rule, Sicily became a trade center in the Mediterranean and had large and prosperous Muslim, Christian, and Jewish communities. Later, Sicily fell to the Normans (tribes of Viking origin). The destruction of Islam in Sicily was completed by the late 1240s, accompanied by pogroms against the Muslim and Jewish populations. If the box is from Sicily, it is probably before 1240, close to al-Jazari’s time.

Safes?

The combination locks make us think of a safe, but these boxes (all three mentioned and al-Jazari’s original) are not safes at all, and the ivory box emphasizes this. There were skilled blacksmiths in the 12th century with very high capabilities in steel, and the fact that the boxes were built of brass or, even worse, ivory means that they were not designed to protect valuable property from burglary. Both al-Kindi (الكندي) and al-Biruni (البيروني) write in the 9th and 10th centuries about steel and forging and specifically about Damascus steel (فولاذ دمشقي), which is a carbon-rich steel that has undergone special processing. Despite its name, Damascus steel originated not in the city of Damascus, but in the region of India, from where it passed to Arab countries. The Europeans, who arrived in the Middle East during the Crusades, brought the swords to Europe. The choice of ivory or brass indicates that these boxes were safely housed in a protected place, like that of the Arthuqid ruler in Diyarbakır. They may have contained documents intended only for the eyes of the ruler and his close advisers, or they may have been beautifully designed with high engineering and aesthetic capabilities.

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A boat which is an alarm clock

Introduction

The device that closes the book is also the simplest of all. In the ancient world, one of the means of measuring time was the submersible float (طرزهار). It’s a buoy with a hole so that the water penetrates and causes it to sink after a given time. This was necessary to monitor the water flow in irrigation canals or for cooking. Al-Jazari feared that the user would nap and miss the sinking of the buoy, so he added a sound effect. It made me search for materials on ancient alarm clocks, which is the subject of this post.

Boat for measuring one hour, Topkapi manuscript, 1205

How does it work?

Sinking buoys don’t require an explanation, so I gave up the traditional blue coloring of the engineering explanations. Obviously, if there is a hole in the buoy, water will penetrate it, and the buoy, or in this case, the boat will sink. The duration of the sinking was achieved by trial and error. Al-Jazari used sinking buoys in the elephant clock and elsewhere. The twist here is the sound alert. I added to al-Jazari’s drawing contours that enclose the airspace and highlights the hole in the bottom:

A drawing by al-Jazari with my additions and captions.

The sailor and boat are made of copper. And they are welded together so that a common airspace is created. At first, the boat sinks slowly, and the trapped air slowly exits under the pressure of the rising water. Due to the slowness of the process, the whistle does not make a sound. There are also five holes for a secondary air exit from the sailor’s hat, which reduce the air output through the whistle and help to silence it. The boat is full of water at the end of the hour, and a rapid sinking begins. The air quickly compresses through the whistle and makes a sound, and helps the sleepy watcher to wake up and do his job.

Early alarm clocks

The earliest alarm clock I have found is associated with Plato, the Greek philosopher. Plato would get up early. In “The Laws,” his last work, he wrote what might explain his need for an alarm clock:

” Asleep, man is useless, he may as well be dead…it a disgrace and unworthy of a gentleman…if he devotes the whole of any night to sleep.”

Plato allegedly designed his own alarm clock. I have reservations because the information comes from Athenaeus of Naucratis,  who wrote the “Deipnosophistae” some 200 years later, and there is no other evidence for this alarm clock. It’s an interesting water clock (not based on a sinking buoy), but in terms of sound play, it’s not very different from Al-Jazari. You can see a nice animation:

There is a good variety of antique alarm clocks. Ctesibius built a particularly precise water clock. We already encountered Ctesibius in a post about A Pump Powered by a Water Wheel. He was an inventor and mathematician in Alexandria, Ptolemaic Egypt, and is best known as the “father of pneumatics.” Very little is known about his life. He was probably the first director of the Museum of Alexandria. His writings have not survived, but his inventions were documented by Athenaeus, I already mentioned, Philo of Byzantium, Heron of Alexandria, and an exceptionally detailed description of the water clock appears in “De architectura, libri decem,” known today as The Ten Books on Architecture by Marcus Vitruvius, a Roman architect and engineer during the 1st century BC. I will expand on the water clock immediately, but Vitruvius also wrote:

 ” At Jaffa in Syria and among the Nomads in Arabia, are lakes of enormous size that yield very large masses of asphalt, which are carried off by the inhabitants thereabouts.”

apparently referring to the Dead Sea. The strange combination of Jaffa, Syria, and the Dead Sea sounds like a child confused by various holidays and mixes Christmas and Chanuka, but this whole Levant may seem like one geographical unit from Rome. This is a good  animation of the clock:

You can see that Ctesibius was aware of the well-known problem of water clocks, which is the variable flow rate with the vessel’s water level. You can read more here. His solution is a tank always full of water, and the excess spills out. This creates a constant flow rate in the second tank, raising the buoy with the indicator indicating the passing minutes. At the end of an hour, the siphon (an invention attributed to Ctesibius) empties the buoy tank and turns the gear counting the hours. Vitruvius writes that there was an “alarm clock system that dropped gravel stones on a gong and blew the trumpets,” but this part has no technical details, so we can only imagine how it worked. A somewhat strange story is that the clock was installed at court in Alexandria and indicated the amount of time lawyers could speak while the severity of the crime determined the amount of water. Ctesibius’ water clock was considered the most accurate until Dutch physicist Christiaan Huygens invented the pendulum clock.

There are other ancient alarm clocks, but it is amusing to know, and says quite a bit about the importance of patents, that a French inventor named Antoine Redier patented an alarm clock in 1847, more than 2,000 years after Plato, who was astonished in his grave and perhaps expected some of the royalties…

 

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The Ritual Ablution (Wuḍū- الوضوء‎) and the Basin of the Slave

 Introduction

This is a basin that allows the ritual ablution (Wuḍū) with the help of an automaton of a young slave who holds a jar of water, a towel, and a comb in his other hand. We have already encountered a peacock that discharges water from its beak, and there are three different tools for Wuḍū that we will meet later. As far as I know, there are no other examples of automatons or “patents” for the ritual Aablution before al-Jazari. I was happy to find out that in 2009 at the Electric Engineers Convention (IEEE) held in Kuala Lumpur, an article was presented on an ” Automatic Ablution Machine using Vision Sensor”  in the hope of saving water. The multitude of tools at al-Jazari can attest to the importance of the ceremony in the Artuqid court in Diyarbakir or that the Ritual Ablution is especially suitable for the desire of al-Jazari for Automaton and allowed him to make use of his favorite siphons and buoys. Either way, it has made me read a little bit more about the wudu, and this will be the center of this post.

The Basin of the Slave, Topkapi Manuscript, 1206

The Ritual Ablution (Wuḍū- الوضوء‎)

Wuḍūʾ in Islam is a ritual purification or ablution done before the prayer. According to tradition, when the prayer, one of the five pillars of Islam, was given to Muhammad, the angel Gabriel came to him, hit the earth with his heel, and the water gushed out. The Angel Gabriel purified himself, and thus Muhammad learned how to do the Wudu. Then he returned home and taught Khadijah, his first wife as well.

The source of the Ritual Ablution is in the words of the Qur’an:

” O you who have believed, when you rise to [perform] prayer, wash your faces and your forearms to the elbows and wipe over your heads and wash your feet to the ankles. And if you are in a state of janabah, then purify yourselves. But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it. Allah does not intend to make difficulty for you, but He intends to purify you and complete His favor upon you that you may be grateful.

Surah 5 -The Table Spread(سورة المائد) verse 6

Muslims believe that physical purity is the basis of spiritual purity and a necessary condition for prayer (الصلاة). This chapter of the Qur’an, or any other, does not detail the ablution process or discuss the full-body ritual purification called Ghusl (غسل). The details of purification appear in the hadith (الحديث), A collection of laws, stories about Muhammad, his way of life, and his statements and advice on various topics. The hadith is second only to the Qur’an.

How does it work?

A young copper slave kneels on a square platform, holding a jug of water in his right hand and a towel and comb in his left hand. At the four corners of the stage are columns bearing a handsome castle with a dome topped by a bird. Adjacent to the stage is a half-basin with a good-looking duck crouching on the floor. From an engineering point of view, all the components, float, and siphons are familiar to me and my readers from al-Jazari’s previous works, respectively, I have given up on the traditional coloring of the text in blue. I’m fascinated by his ability to connect them each time in a way that really tells a story, and in this case, the story is the appearance and disappearance of the ablution waters. This is the diagram of the mechanism with captions that I added:

The servant brings the device when the tank is filled with the amount of water necessary for the purification ceremony and pulls the plug. Water goes down the pipe hidden in the castle column and through the young slave’s arm reaches the top of the jug. This whole path is concealed to enhance the wonder of the automata and its operation. The spout is a siphon that reaches the bottom of the water jug. I’ve written about siphons here. The water will not come out until the water level exceeds the arc of the siphon. The air in the jar has no outlet; apart from the thin tube attached to the whistle, the king would imagine the bird on top singing for him and announcing that the ceremony is beginning. Soon after, the water in the jug will reach a sufficient height, and the water will come out of the spout and allow the king to perform the purification. The water will be collected in the adjacent sink, but the latter lacks a drain, so the water will accumulate. The handsome duck at the bottom of the sink is also a siphon, and when the water reaches a height indicating that the ceremony has ended, the duck will empty the sink into the lower water tank. In this container, a float is attached by a chain to the slave’s left arm, located on a hinge. When the float rises, it will release the arm, which will move, offering the king the towel and comb.

 

Reflections on the Basin

While wandering, I tried to imagine the Artuqid ruler Nasir al-Din Mahmud making the Wudu with al-Jazari’s automata. The Wudu includes several components, and there are differences between Sunnis and Shiites. We begin by connecting the bathing to the ablution ritual by reciting (possibly only in the heart) the Basmala (Arabic: بَسْمَلَة, = بِسْمِ ٱللَّٰهِ ) literally “In the name of Allah but  a short of the Islamic phrase “In the name of God, the Most Gracious, the Most Merciful.”This is followed by a ritual washing that includes a triple wash of the face, including washing the mouth and nose, triple washing of the hands, including elbows, symbolic cleaning of the head with water (مسح), and bathing both legs up to the ankles. We conclude by saying the Shahada ( ٱلشَّهَادَةُ), which is the Islamic oath: “There is no god but Allah, and Muhammad is His messenger.”

Wudu bathing at the entrance to the mosque in Dashahi. Photo by Pale blue dot

The ablution is thus a part of the prayer and “justifies” Al-Jazari’s multiple devices. On the other hand, there is something playful and amusing about the basin of the slave that contradicts (in my mind) the seriousness of the ceremony. But maybe it’s just me, and in the 12th century, prayer sat perfectly with the wonder of the water appearing and disappearing like a magic wand.

 

 

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The clock of the doors and the Jewish question

Introduction

The clock of the doors is identical to the candle clock of the monkey in terms of its mechanism and does not warrant a separate post. Just like the old joke about “The Elephant and the Jewish Question,” the clock of the doors has nothing to do with Jews,  which are not mentioned in the “The Book of Knowledge of Ingenious Mechanical Devices” even once. The phrase “The Elephant and the Jewish Question” is usually used to describe an annoying person who tries to link any event, however universal, to the Jewish people and their problems. I hope I’m not one of them, and I don’t have any convincing reason why I went out to check what we know about the Jews of Diyarbakır and Anatolia in the 12th Century. However, what I discovered is strange and exciting, and maybe it will interest you too.

The Candle Clock of the Doors” The Book of Knowledge of Ingenious Mechanical Devices, “Topkapi manuscript, 1206

How does it work?

Al-Jazari himself wrote:

” It is like the previous model, from which nothing is omitted except the keeper and the monkey. The additions are as follows: around the perimeter of the candle holder, fourteen doors are erected, each with two leaves. When a constant hour has passed from the lighting of the wick, a ball falls from the falcon’s beak, and the door opposite the falcon opens, and a figure emerges, [made] according to the choice of the craftsman.”

Anyone interested in the mechanism can go back and read my explanation of the monkey clock or the candle clock of the scribe. I will briefly explain the opening of the doors.

During combustion, the candle will shorten, and the force exerted by the weight will push the candle mount upwards at a constant rate that depends on the rate of combustion. To the bottom of the weight is attached another wire that runs over the pulley on which the bracket sits with 14 doors. These rotate as the candle burns. When the ball falls, it pushes the figure who opens a door and represents the time that has passed. This process repeats itself every hour.

The Jews in the 12th Century

The history of the Jewish people in the 12th Century is not similar in Ashkenazi communities and Muslim Spain. In Europe, the 12th Century began with the Rhineland massacres, a series of mass murders of Jews perpetrated by mobs of the People’s Crusade in 1096. The communities on the Rhine (Speyer, Worms, and Mainz) were destroyed. In 1146, in a repeat of the events of 1096, Crusaders preparing for the Second Crusade attacked and massacred Jewish communities along the Rhine. The 12th Century more or less ended with One of the worst Jews massacres of the Middle Ages, which took place in York in 1190. An angry mob trapped the city’s entire Jewish community inside the tower of York Castle. Many members of the community chose to commit suicide rather than be murdered or forcibly baptized by the attackers.

In Spain, on the other hand, Jewish people under Muslim rule experienced tolerance and integration. Some historians refer to this period as the “Golden Age” for the Jews, as more opportunities became available to them. That lasted from the days of the Caliphate of Cordoba to the small independent Muslim principalities and kingdoms of the Iberian Peninsula known as “taifas” and the process of the reconquest of Spain by the Christians. Social integration allowed Jews to advance significantly in new fields, philosophy and science. Some of them wrote poetry, primarily Hebrew poetry. They wrote about everything: poems about Zion and the people of Israel, but also poems about wine and women. I don’t think there’s a connection between the cultural flourishing in Diyarbakır and the Jewish flourishing in Muslim Spain, but it’s still intriguing. The Golden Age began in the 9th Century and ended in the 13th Century, but some of the more familiar figures were almost parallel to al-Jazari. For example, Maimonides was born in Cordoba in 1138, two years after al-Jazari, and died in Cairo in 1204, two years before him. Maimonides is a true polymath: one of the most prolific and influential Torah scholars of all generations, as well as a prominent philosopher of the Middle Ages, a scientist, and a physician. In his thirst for wisdom, he formed a study group and a friendship with Jabir ibn Aflah (a Muslim scholar) ‘s son, and they studied mathematics, medicine, and philosophy together. This must sound strange to those who live in Israel today and are familiar with the ultra-Orthodox opposition to secular studies. The “Kuzari” book, ” Book of Refutation and Proof on Behalf of the Despised Religion,” which I still managed to study in high school, was written by Rabbi Yehuda Halevi in this Century, and I must mention Rabbi Abraham Ibn Ezra, a 12-century poet, linguist, biblical commentator, and philosopher. He also worked in mathematics and astronomy. One of the lunar craters is named after him. Ibn Ezra’s most important mathematical work is in Hebrew: “The Book of the Unit,” which deals extensively with the decimal system and how it is used, thus preceding Fibonacci, the main contributor to the spread of this method in the Western world.

Did al-Jazari know the books they wrote or even heard about them? It is impossible to know, but the likelihood is extremely low.

Jews in Diyarbakır

In 1518, the Ottoman government conducted a census. There were 28 Jewish families and three single men in Diyarbakır. These are the first definitive data we have. After that, a continuous Jewish presence peaked in 1905, but apparently, the presence of Jews in Anatolia predates the Muslim conquest. According to traditions held by the Jews of Kurdistan, the Jews arrived in Kurdistan as early as the Salomon’s Temple period and are descendants of the Ten Tribes. As written in the book of  Kings:

” In the ninth year of Hoshea, the king of Assyria took Samaria, and carried Israel away unto Assyria, and placed them in Halah, and in Habor, on the river of Gozan, and in the cities of the Medes.”

Although we do not have a complete geographical identification, the name “Habur” has been preserved to this day as one of the Tigris tributaries located near the city of Zaxo (Arabic: زاخو), about 300 km from Diyarbakir. Later exiles to Babylon by Nebuchadnezzar, King of Babylon from the Kingdom of Judah, joined them. So it is very likely that there were Jews in Diyarbakir in al-Jazari’s day.

A Jewish delegation meeting with an Ottoman official

The Strange Story of David Alroy

Alroy was born a year before al-Jazari in Amadiya, Kurdistan. At first, I was confused because the historical name of Diyarbakır is Amida, but these are two different cities. Amadiya is located in northern Iraq, about 400 km southeast of Diyarbakir. David Alroy studied rabbinical literature with Hasdai, the exilarch, the leader of the Jewish community in Persian Mesopotamia, and Ali Gaon, the head of the Sanhedrin,  an assembly of elders appointed to sit as a tribunal in Baghdad. There is a claim that he was also well-versed in all the Books of Magic and sorcerers. I’m not sure what books are included, but it’s a bit like Chekhov’s gun, which appears in the first act, firing in the third. I have already mentioned Benjamin of Tudela, and not for the better. He wrote:

” David Alroy took upon him to rebel against the King of Persia [in 1163] ; for which purpose he gathered together all the Jews on the Mountains of Haphton, and from other Nations, to go to lay Siege to Jerusalem A great Part therefore of the Jews had Faith in; him, calling, him their Messiah. As soon as the King of Persia heard of this Matter, he commanded him to be brought before him. The King asked him: “Are thou the King of the Jews?” He answered and said, “I am,” The King then called to his Guards, and commanded him immediately to be apprehended, and led away to prison in the City of Dabastan. Three Days after this, as the King was sitting together with his Princes and Chief Minitiers, deliberating about the Jew Rebellion, behold David, having made his Escape from prison and approached and stood before him. The King looked at him and enquired, “Who brought thee hither?” He answered: “My own wisdom, and my own Subtilty because I fear neither thee nor any of thy Servants.” At which the King cried out: “Seize him!” But his servants said: “We see him not, but only hear the sound of his voice.”

Alroy then crosses the river on his handkerchief, and the King’s servants are unable to catch him in their boats. The King threatened to kill all the Jews in his kingdom. The frightened Jewish community threatened Alroy with a total exclusion from the Jewish community (“HEREM”). “In the end, David Alroy was killed in his bed while sleeping.

The story has legendary elements (seeing and not being seen, walking on water) absent in the description of Alroy’s contemporary, Al-Samawʾal ibn Yaḥyā al-Maghribi, who converted to Islam. To me, comparing the stories is less important than the passage describing the Baghdad Jews’ yearning for redemption:

“In this letter [a letter that two men forged in the name of David Alroy], they announce to the Jews of Baghdad the coming of the redemption they have been waiting for generations, in which they determine the night when they will all fly to Jerusalem, the holy city. Although the Jews of Baghdad were proud of their wisdom and strength of mind, they nevertheless tended to believe in this thing. Their wives brought all their possessions and jewelry to these two men so that they could divide all the property as they saw fit. In this way, the Jews wasted all their possessions. They wore green clothes and gathered that night on the rooftops of the houses, eagerly awaiting the moment when they would fly on the angels’ wings straight to Jerusalem. The women raised their voices in tears because they feared that they themselves would fly first before their children or the babies they were breastfeeding, and then these babies would suffer hunger.”

It is pretty clear that the Crusades and the instability in Palestine and nearby countries resonated strongly with some Eastern Jews, who saw them as precursors of redemption. The fantastic picture of the preparations for the flight and the heartbreak of the morning after also appear in other sources. Was all this commotion the talk of the day in Diyarbakir? This time not in distant Cordoba but in neighboring Amadiya,? We don’t know; even if it did, it must have been a minor event in al-Jazari’s world.